"In 2006, an estimated 1,205,273 persons were convicted of a felony (federal and state courts). Of that number, 1,132,290 were convicted in state courts, the vast majority (94 percent) of whom pleaded guilty. At the time of sentencing, about 3 out of 4 felons sentenced (77 percent) were sentenced for a single felony."

The accompanying data table shows that 377,860 (33.4%) of these convictions were for Drug Offenses, of which 165,360 (14.6% of all convictions) were for Possession and 212,490 (18.8% of all convictions) were for Trafficking.

Note: The 2012 Statistical Abstract was the last one published: "The U.S. Census Bureau terminated the collection of data for the Statistical Compendia program effective October 1, 2011."

Source

Statistical Abstract of the United States: 2012. Section Five: Law Enforcement, Courts, and Prisons. Washington, DC: US Department of Commerce, Economics and Statistics Administration. August, 2011.